An ink cartridge that is opened to the atmosphere and that contains liquid ink and an ink jet recording apparatus (ink jet printer) to which the ink cartridge is exchangeably attached are examples of a known liquid storage container and a known liquid-consuming apparatus, respectively.
The ink cartridge generally has a container main body that is detachably attached to a cartridge-receiving unit of the ink jet recording apparatus. The container main body includes an ink storage chamber that is filled with ink, an ink-supplying unit for supplying the liquid contained in the ink storage chamber to the ink jet recording apparatus, an ink guide path through which the ink storage chamber and the ink-supplying unit communicate with each other, and an atmosphere communicating path for allowing air to flow into the ink storage chamber from the outside as the ink contained in the ink storage chamber is consumed. When the ink cartridge is attached to the cartridge-receiving unit of the ink jet recording apparatus, an ink supply needle included in the cartridge-receiving unit is connected to the ink-supplying unit by being inserted therein, so that the can be supplied to a recording head included in the ink jet recording apparatus.
The recording head included in the ink jet recording apparatus controls an operation of ejecting ink drops using heat or vibration. If the ink-ejecting operation is performed when there is no more ink in the ink cartridge and no ink can be supplied, the recording head will break down. Therefore, in the ink jet recording apparatus, it is necessary to monitor the amount ink remaining in the ink cartridge so as to prevent the recording head from operating when there is no ink.
In light of the above situation, an ink cartridge has been developed which includes a liquid remaining-amount sensor that outputs a predetermined electrical signal when the amount of ink remaining in a container main body is reduced to a predetermined threshold, so that a recording head included in a recording apparatus can be prevented from operating after the ink contained in the ink cartridge runs out (see, for example, JP-A-2001-146030).
In the known ink cartridge that is opened to the atmosphere, the ink storage chamber is always vented to the atmosphere through the atmosphere communicating path. Therefore, moisture included in the ink stored in the ink storage chamber is evaporated through the atmosphere communicating path. Accordingly, viscosity of the ink is increased due to the evaporation of the moisture. As a result, there is a risk that the printing performance of the ink jet recording apparatus will be influenced.
In addition, since natural ventilation of the atmospheric air in the ink storage chamber occurs through the atmosphere communicating path, the ink contained in the ink storage chamber often comes into contact with fresh air. Therefore, in the long view, there is a possibility that the quality of the ink will be degraded due to the contact with air.